Applicants have found that when attaching one end of a vacuum hose to the usual hinged saw guard and the other end to a relatively strong vacuum source, such as a shop-vac, that small cut off work pieces were likely to be picked up and sometimes drawn into the hose. This not only causes inconvenience it also presents a hazardous situation.
In a U.S. Pat. No. 4,367,655 for a sawdust collection system the joint inventors, Daniel A. Terpstra and Richard B. Brundage, of the present application disclosed a sawdust collection system for a motorized table saw. This earlier disclosure included a flexible hose connected at one end to a hinged saw guard and at its other end to a vacuum source of known capacity comprising a centrifugal blower connected to and driven by an outboard mounted saw driving motor. In this case the capacity of the vacuum source to cause an airflow velocity through a hose of a specific size was known to be low enough to avoid the pickup of small work pieces and it was stated that, "The capacity of the blower and the diameter of the connecting hose is such as to cause a relatively large volume airflow through the saw guard at a relatively low rate of flow so as to collect virtually all of the fine sawdust likely to become airborne without withdrawing any appreciable amount of the larger heavier particles."
In the present invention applicants have provided a specially formed hinged saw guard having provision for the convenient detachable connection thereto of a vacuum hose which permits a sufficient flow of air into the hose from the exterior of the guard as well as from the interior thereby to limit the velocity of airflow through the guard and preclude the picking up of small cut off work pieces when an available, relatively strong vacuum is applied to the other end of the hose. This bleeding of exterior air into the vacuum hose not only reduces the velocity of airflow through the guard to preclude the pickup of small cut off work pieces it also induces the flow into the hose of fine sawdust particles thrown alongside of the guard by the saw blade when the hinged guard is raised from the worktable by a workpiece.
Another problem encountered was the emission of sawdust from the saw base through the sizeable arcuate aperture in the front wall of the base provided to permit the saw elevating screw, which passes therethrough, to swing with the tilting of the saw blade. In the earlier application referred to herein above the applicants provided a strip of foamed material enclosing this arcuate aperture. While this expedient is effective in preventing the escape of sawdust through this aperture, an objectionable amount yet escaped around the elevating screw due to the considerable velocity at which sawdust is thrown toward this aperture by the saw blade. To effectively solve this problem applicants in the present invention have provided a U-shaped deflector tiltable with the saw blade for directing all below table sawdust off the saw blade downwardly into a collector bag attached to the open bottom of the base.